1. Field of the Invention
The present invention relates to electronic modules and, in particular, to such modules using commercial grade components which are protected from heat, cold and other environmental degradation, to the extent of being qualifiable under military specifications.
2. Description of Related Art and Other Considerations
Militarily and space qualified electronic components, e.g., chips in ceramic packages, are used in such modules as computer processing units (CPU's). Military specifications require such components to have a case temperature which is rated from -50.degree. C. to 125.degree. C., with a maximum junction temperature of 150.degree. C. or more.
Commercial and industrial rated plastic encapsulated parts have a maximum junction temperature ranging from +85 to +115.degree. C., because the die and encapsulant used in these parts have radically different coefficients of thermal expansion. Commercial parts are not rated below 0.degree. C., and industrial only parts to -40.degree. C. The market for militarily qualified parts with the performance of those found, for example, in common desk top personal computers has not been reason enough for manufacturers to produce these parts. Therefore, commercial and industrial grade components are not currently qualified for military applications.
However, commercial and industrial components are considerably cheaper than their functionally corresponding military components. For this reason, it would be most desirable if commercially rated RISC and other microprocessors and other highly integrated plastic packaged chips could be used in a high performance computer processing unit design for military applications.
In addition, such components must be cooled and/or heated. For military and space use, it is essential that the components and the equipment in which they are used weigh as little as possible and be compactly packaged. Thus, fans and like cooling apparatus employed in commercial and industrial applications are not suitable for such use.